Now on the topic of the whole KI scene: Competition is very high on zbattle, and some players new to the scene but interested in fightin good players might find this lil "list" somewhat handy when it comes down to lookin for good matches.
JAG
SaBrE
Atmos
BentLeeT
replicant (also goes by "Ciggar" / "Roman")
Jin
Ultima
-D-Hunter
Combo2 (also goes by "Sgt.PeterFuck")
redeyedol <--- that's me, roar
wavedasher
paul
JinKazama
These guys are some of the best KI players you could ever find (and I am one of them, hehe), so make sure you play them if you want to get your asses kicked.
If anyone has any questions on all this stuff, I'll be glad to answer them and help you in anyway I can. 
..yes, I know Killer Instinct is a game over 12yrs old, and although it is "officially" dead in the mainstream, it is still quite popular. The scene is kinda underground, but it is actually quite alive and very active, so this game is definitely somethin to give a try - good stuff from the mid 90s.